I could of sworn i either found the answer to this question or asked it myself before but i searched and could not find it on the forum. so here it is. Can i use a normal metal halide through the flowering stage?
Use them both. It has been said that you will more than likely lose some bud production potential if you go with metal halide all the way. You really want the color spectrum of the hps for flowering. But if thats all you have it will work.
I did metal halides all the way, if you're only doing a small personal grow, then it's going to be fine. I probably could have gotten more of a yield if I had switched to an HPS, but I didn't have the money for it. Anyway, it went just fine for me, in fact I just cut down one of my plants the other day and it looks awesome. I would recommend that if you decide to go metal halide all the way that you get this bulb: http://www.planetnatural.com/site/agrosun-gold.html It's a metal halide that emits more of the red light spectrum than other halides. So it's more useful for the whole grow. Good luck.
Or use this one http://www.htgsupply.com/productdetail.asp?productID=370 as its close to the 2700 calvin of a HPS and $10 cheaper!
Does anyone out there have data on a side by side comparison grow with the clones grown under the same regime but flowered under mh vs hps for thc content? I had heard anecdotal evidence from different folks back in the day who seemed to feel their mh's were more potent... Other anecdotal evidence seems to back up that mh makes a denser tighter harder nug....